/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#define LOG_TAG "Tokenizer"

#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/stat.h>
#include <utils/Log.h>
#include <utils/Tokenizer.h>

// Enables debug output for the tokenizer.
#define DEBUG_TOKENIZER 0


namespace android {

    static inline bool isDelimiter(char ch, const char *delimiters) {
        return strchr(delimiters, ch) != NULL;
    }

    Tokenizer::Tokenizer(const String8 &filename, FileMap *fileMap, char *buffer,
                         bool ownBuffer, size_t length) :
            mFilename(filename), mFileMap(fileMap),
            mBuffer(buffer), mOwnBuffer(ownBuffer), mLength(length),
            mCurrent(buffer), mLineNumber(1) {
    }

    Tokenizer::~Tokenizer() {
        delete mFileMap;
        if (mOwnBuffer) {
            delete[] mBuffer;
        }
    }

    status_t Tokenizer::open(const String8 &filename, Tokenizer **outTokenizer) {
        *outTokenizer = NULL;

        int result = NO_ERROR;
        int fd = ::open(filename.string(), O_RDONLY);
        if (fd < 0) {
            result = -errno;
            ALOGE("Error opening file '%s': %s", filename.string(), strerror(errno));
        } else {
            struct stat stat;
            if (fstat(fd, &stat)) {
                result = -errno;
                ALOGE("Error getting size of file '%s': %s", filename.string(), strerror(errno));
            } else {
                size_t length = size_t(stat.st_size);

                FileMap *fileMap = new FileMap();
                bool ownBuffer = false;
                char *buffer;
                if (fileMap->create(NULL, fd, 0, length, true)) {
                    fileMap->advise(FileMap::SEQUENTIAL);
                    buffer = static_cast<char *>(fileMap->getDataPtr());
                } else {
                    delete fileMap;
                    fileMap = NULL;

                    // Fall back to reading into a buffer since we can't mmap files in sysfs.
                    // The length we obtained from stat is wrong too (it will always be 4096)
                    // so we must trust that read will read the entire file.
                    buffer = new char[length];
                    ownBuffer = true;
                    ssize_t nrd = read(fd, buffer, length);
                    if (nrd < 0) {
                        result = -errno;
                        ALOGE("Error reading file '%s': %s", filename.string(), strerror(errno));
                        delete[] buffer;
                        buffer = NULL;
                    } else {
                        length = size_t(nrd);
                    }
                }

                if (!result) {
                    *outTokenizer = new Tokenizer(filename, fileMap, buffer, ownBuffer, length);
                }
            }
            close(fd);
        }
        return result;
    }

    status_t Tokenizer::fromContents(const String8 &filename,
                                     const char *contents, Tokenizer **outTokenizer) {
        *outTokenizer = new Tokenizer(filename, NULL,
                                      const_cast<char *>(contents), false, strlen(contents));
        return OK;
    }

    String8 Tokenizer::getLocation() const {
        String8 result;
        result.appendFormat("%s:%d", mFilename.string(), mLineNumber);
        return result;
    }

    String8 Tokenizer::peekRemainderOfLine() const {
        const char *end = getEnd();
        const char *eol = mCurrent;
        while (eol != end) {
            char ch = *eol;
            if (ch == '\n') {
                break;
            }
            eol += 1;
        }
        return String8(mCurrent, eol - mCurrent);
    }

    String8 Tokenizer::nextToken(const char *delimiters) {
#if DEBUG_TOKENIZER
        ALOGD("nextToken");
#endif
        const char *end = getEnd();
        const char *tokenStart = mCurrent;
        while (mCurrent != end) {
            char ch = *mCurrent;
            if (ch == '\n' || isDelimiter(ch, delimiters)) {
                break;
            }
            mCurrent += 1;
        }
        return String8(tokenStart, mCurrent - tokenStart);
    }

    void Tokenizer::nextLine() {
#if DEBUG_TOKENIZER
        ALOGD("nextLine");
#endif
        const char *end = getEnd();
        while (mCurrent != end) {
            char ch = *(mCurrent++);
            if (ch == '\n') {
                mLineNumber += 1;
                break;
            }
        }
    }

    void Tokenizer::skipDelimiters(const char *delimiters) {
#if DEBUG_TOKENIZER
        ALOGD("skipDelimiters");
#endif
        const char *end = getEnd();
        while (mCurrent != end) {
            char ch = *mCurrent;
            if (ch == '\n' || !isDelimiter(ch, delimiters)) {
                break;
            }
            mCurrent += 1;
        }
    }

} // namespace android
